Inventors have long been concerned with devising penetration resistant panels to serve as doors for safes and vaults.
A more-or-less conventional approach to penetration resist is to pack the interior of the panel with layers of tough materials, such as, metal screen, ceramic, gypsum and mineral fibers. This is the approach advocated by U.S. Pat. No. 5,060,582 granted Oct. 29, 1991 to H. Salzer for “High Security Blast Resistant Door Leaf”.
U.S. Pat. No. 4,178,859 granted Dec. 18, 1979 to R. Seiz et al. For “Door-Like Closure” proposed a door structure possessing a multi-layer front plate backed up by a metal grid providing an array of apertures to permit pressure shock from an explosive assault on the door to pass through the structure with minimal damage to the structure.
A different approach was suggested in U.S. Pat. No. 6,240,858 granted Jun. 5, 2001 to M. C. Mandall for “Penetration Resistant Panel”. In this patent the panel contains a plurality of elongated members in a serpentine configuration under axial compression. The members are adapted to straighten to extend into an opening cut or blasted through the panel and the members.
While these prior art approaches to penetration resistance are somewhat effective, there continues to be a need for an improved penetration resistance panel which is relatively easy to manufacture and is particularly effective in resisting not just one, but repeated explosive attacks.